So-called notebook personal computers and the like are configured such that, in order to reduce the size of their main body, external storage devices such as FD and CD-ROM drives can be connected thereto by means of connectors. Also, such a notebook personal computer is typically constructed so as to use a rechargeable battery (so-called battery pack) as its power supply.
In order to connect with an external storage device, a signal connector having about 80 pins of signal contacts is necessary, while a power connector having a power contact with a capacity larger than that of the signal contacts is required for connecting with a battery pack. When both the signal connector for connecting with the external storage device and the power connector for connecting with the battery pack are provided, the notebook computer, which has a limited space for utilizing connectors, is likely to increase in size.
Accordingly, the connector utilized in the personal computer may be configured so as to be used as both signal connector and power connector, such that the external storage device and the battery pack can selectively be connected thereto when necessary. A conventional commonly usable connector is one in which two poles of power contacts are respectively disposed at right and left end portions of a plurality of signal contacts aligned in the right-to-left direction.
In the thus configured personal computer, each connector is attached thereto by means of a securing metal part disposed at the housing of the connector. While each connector is constituted by a plug connector and a receptacle connector as mentioned above, a case or circuit board to which the plug connector or receptacle connector is to be attached individually has a ground, and each securing metal part is connected to this ground.
Since the case and circuit board having respective connectors attached thereto may have different potentials, however, a potential difference may be generated between the case and circuit board when the connectors are mated together, thereby causing a noise to occur.
Also, in the connector configured as mentioned above, there are cases of so-called hot-plugging, in which the connectors are mated together or detached from each other while electric power is supplied to the power contacts. When the connectors are mated together while electric power is supplied to the power contacts, however, a voltage or current higher than the rated level may flow (generating a so-called "peak") at the time when the contacts are connected to each other, thereby generating a noise, which may be mistaken as other signals. Thus, hot-plugging may cause undesirable affects.